MPXV and SARS-CoV-2 in the air of nightclubs in Spain
Authors: África Sanchiz, Rocío Martín, Margarita Del Val, Alfredo Corell, Antonio Alcamí
Journal: The Lancet Microbe (2023)

The COVID-19 pandemic has highlighted the relevance of airborne transmission of respiratory viruses.1Wang CC Prather KA Sznitman J et al.Airborne transmission of respiratory viruses.Science. 2021; 373eabd9149Crossref Scopus (441) Google Scholar The risk of airborne SARS-CoV-2 exposure in public indoor spaces, in addition to hospitals, has been debated but experimental evidence is scarce.2Ramuta MD Newman CM Brakefield SF et al.SARS-CoV-2 and other respiratory pathogens are detected in continuous air samples from congregate settings.Nat Commun. 2022; 134717Crossref PubMed Scopus (6) Google Scholar The mpox (formerly known as monkeypox) outbreak, a WHO Public Health Emergency of International Concern, primarily affects men who have sex with men (MSM). Monkeypox virus (MPXV) transmits by contact with skin lesions, fomites, and respiratory secretions,3Gessain A Nakoune E Yazdanpanah Y Monkeypox.N Engl J Med. 2022; 387: 1783-1793Crossref PubMed Scopus (80) Google Scholar but detection of MPXV DNA in hospital air samples opens the possibility of alternative transmission routes.4Gould S Atkinson B Onianwa O et al.Air and surface sampling for monkeypox virus in UK hospitals.Lancet Microbe. 2022; 3: e904-e911Summary Full Text Full Text PDF PubMed Scopus (27) Google Scholar, 5Hernaez B Muñoz-Gómez A Sanchiz A et al.Monitoring monkeypox virus in saliva and air samples in Spain: a cross-sectional study.Lancet Microbe. 2022; 4: e21-e28Summary Full Text Full Text PDF PubMed Scopus (20) Google Scholar We monitored SARS-CoV-2 and MPXV genomes in the air in six bar areas and one dark room (sex room) in Madrid nightclubs frequently visited by MSM during four weekend days in 2022 (July 8, July 16, Aug 8, and Nov 5). To sample aerosols, air samples were collected in nanofibre filters3Gessain A Nakoune E Yazdanpanah Y Monkeypox.N Engl J Med. 2022; 387: 1783-1793Crossref PubMed Scopus (80) Google Scholar located behind the club bar or in a central location of the dark room away from customers (>2 m distance), and viral genomes were detected by quantitative PCR (appendix p 2). All air samples from July were positive for SARS-CoV-2, with 12 (86%) of 14 samples containing more than 50 genomes per m3, and three samples even reaching more than 1000 genomes per m3 (appendix pp 4, 5). These findings were consistent with epidemiological data that showed a high prevalence of COVID-19 among people older than 60 years in Spain at the time. All except one of the air samples from August and November were negative for SARS-CoV-2. On July 8, which coincided with the gay pride parade in Madrid, MPXV DNA was undetectable in the air, with the exception of one sample, and on July 16, it was detected in two samples. MPXV in the air had increased considerably on Aug 8, with four (57%) of seven positive samples containing more than 100 genomes per m3, or even more than 1000 genomes per m3 in one case; this date coincided with the peak incidence of mpox in Spain. High viral loads in the air were detected in the dark room but also in bar areas, sometimes even at higher concentrations. MPXV was undetectable in November. Carbon dioxide concentrations were very high in all nightclubs, indicating poor ventilation and a high risk of airborne transmission (appendix p 5). To our knowledge, this is the first evidence of airborne SARS-CoV-2 and MPXV in nightclubs. Aerial virus monitoring corresponded with epidemiological incidence, indicating that it is a reliable tool to evaluate environmental risks of infection. MPXV was previously detected in the air of health centre consulting rooms,4Gould S Atkinson B Onianwa O et al.Air and surface sampling for monkeypox virus in UK hospitals.Lancet Microbe. 2022; 3: e904-e911Summary Full Text Full Text PDF PubMed Scopus (27) Google Scholar and we showed high virus levels in the air of indoor public spaces, presumably exhaled from people who were infected with MPXV. This finding suggests that MPXV exposure occurs beyond skin or sexual contact, and future studies to address airborne monkeypox virus transmission are warranted. If COVID-19 or mpox cases rise in the future, people attending mass events or indoor public entertainment venues should be made aware of the risk of airborne exposure to these viruses. For epidemiological data for mpox see https://ourworldindata.org/monkeypox For epidemiological data for mpox see https://ourworldindata.org/monkeypox We declare no competing interests. We thank the invaluable collaboration of the MSM community and the contribution of the staff from the five nightclubs in Madrid. This work was funded by the EU (Nextgeneration EU) and Consejo Superior de Investigaciones Científicas (PTI Salud Global). Download .pdf (.33 MB) Help with pdf files Supplementary appendix